Phenolics from bilberries ( Vaccinium myrtillus L.) sampled from seven different locations and highbush blueberries ( Vaccinium corymbosum L.) from one location in Slovenia were analyzed. In samples of both species 15 anthocyanins were identified by LC-MS/MS. Their contents were expressed as cyanidin 3-glucoside equivalents (C3GE); bilberries contained 1210.3 ± 111.5 mg C3GE/100 g fw and blueberries 212.4 ± 14.1 mg C3GE/100 g fw. Glycosides of delphinidin and cyanidin were predominant (488.5 vs 363.6 mg C3GE/100 g fw) in the bilberries and glycosides of malvidin (108.0 vs 100.8 mg C3GE/100 g fw) in the blueberries, whereas the contents of peonidin were lowest (74.5 vs 4.8 mg C3GE/100 g fw) in both berries. The contents of flavanols, flavonols, phenolic acids, and stilbenes were determined by LC-MS. For the first time, rutin was identified (bilberries, 0.2 ± 0.0 mg/100 g fw; blueberries, 3.1 ± 0.1 mg/100 g fw). Chlorogenic acid (as 3-caffeoylquinic acid) was the most abundant among the phenolic acids (23.1 ± 1.0 mg/100 g fw in bilberries and 70.0 ± 3.4 mg/100 g fw in blueberries). Statistical analysis shows that the content of 27 individual flavonoids, phenolic acids, and stilbenes can be used to identify the picking region of these Slovenian bilberries.

Despite being reported to reduce the risk of cardiovascular diseases, little is known about acute direct effects of bilberry anthocyanins on whole mammalian heart under ischemia-reperfusion (I-R) conditions. Bilberry anthocyanins were prepared from the ripe bilberries and analyzed using HPLC-DAD. Their antioxidant activity was evaluated by measuring the intrinsic free radical-scavenging capacity and by cellular antioxidant assay (CAA) on endothelial cells, where we quantified the intracellular capacity to inhibit the formation of peroxyl radicals. Experiments on the isolated rat hearts under I-R were carried out according to the Langendorff method. Perfusion with low concentrations of bilberry anthocyanins (0.01-1 mg/L) significantly attenuated the extent of I-R injury as evidenced by decreasing the release rate of LDH, increasing the postischemic coronary flow, and by decreasing the incidence and duration of reperfusion arrhythmias. High concentrations (5-50 mg/L) diminished cardioprotection and show cardiotoxic activity despite having their radical scavenging and intracellular antioxidant capabilities increased in a concentration-dependent manner. This study reveals the biphasic concentration-dependent bioactivity of bilberry anthocyanins under I-R, which results in strong cardioprotective activity in low concentrations and cardiotoxic activity in high concentrations.

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Background Bilberries (Vaccinium myrtillus L.) are recognized as a good source of flavonoids, especially anthocyanins, which have strong antioxidative activity. Therefore, they may have a strong potential as cardioprotective agents in ischemicreperfusion injury.